The role of lake physical characteristics in shaping the net surface energy budget of a lake: from local to global

Abstract:

Lakes have been described as "sentinels of climate change" due to their sensitivity to changes in climate and catchment hydrology. However, beyond the scale of an indivudal lake, quantifying their contribution to global energy and carbon budgets and their responses to climate change is not trivial. In this study we have undertaken an analysis of the results of a multi-lake modelling project in an attempt to characterise how the slope of the net energy exchange vs average annual air temperature relationship is affected by physical lake characteristics. For the initial study, 30 lakes with a variety of morphometries, climatic, hydrological and trophic characteristics were simulated for a period of 2 years using a the General Lake Model (GLM), a simple 1-D hydrodynamic model. The physical mixing parameters used to quantify heat and momentum budgets were determined using a Markov Chain Monte Carlo (MCMC) approach that optimised model output to observed temperature profile data. Surface energy budget components, as calculated by the model for each lake, were then compared to a variety of lake metrics, such as lake depth, volume and residence time, to quantify relationships between the slope of the net energy and air temperature curve. The analysis demonstrates that integration of numerical models with data from a global sensor network can be an effective way to parameterise complex relationships between limnological characteristics and energy budgets.